Immunonutrients and the Critically Ill Neonate

Abstract

After completing this article, readers should be able to: 1. List the otherwise “nonessential” nutrients that may be required by the critically ill neonate. 2. Explain why omega-3 fatty acids do not cause as much inflammation as their omega-6 counterparts. 3. Define pre- and probiotics and describe how they can prevent colonization of the intestine by pathogenic organisms. 4. Describe the potential protective effects of lactoferrin on the neonatal gastrointestinal tract. In a critically ill individual, the intestinal barrier becomes compromised because of stress, lack of enteral feedings, and ischemic-reperfusion injury. In the preterm neonate, the mucosal barrier is not fully functional (see article on innate immunity in this issue of NeoReviews ). The combination of a damaged and immature gut barrier may lead to increased intestinal permeability, aberrant antigen transfer, and immune response, which can explain the vulnerability to infection, inflammation, and hypersensitivity at an early age. In patients dying of sepsis, there is clear evidence of an imbalance in pro- and anti-inflammatory cytokine production, a failure to maintain antioxidant defenses, and high levels of activation of nuclear factor- kappa-B (NF-kappa-B). Over the past several years, it has become more evident that the proinflammatory cytokine response, as part of an uncontrolled systemic inflammatory response syndrome (SIRS), plays an integral role in premature labor, chronic lung disease, cerebral palsy, necrotizing enterocolitis (NEC), and sepsis. Because the gut is a primary origin of SIRS, it is reasonable to suggest that nutritional agents might stabilize the intestinal mocosal barrier, alter the balance of pro- and anti- inflammatory cytokines, and prevent excessive activation of NF-kappa-B or other signaling pathways. Some nutrients, such as glutamine, arginine, omega-3 fatty acids, nucleotides, and probiotics, have been shown to have a considerable influence on immune function (eg, delayed hypersensitivity, lymphocyte subpopulation counts, immunologic test) and improve metabolic and nutritional indices such as …